private InMemoryMarkerOverlay markerOverlay;
        private void WpfMap_Loaded(object sender, RoutedEventArgs e)
        {
            wpfMap1.MapUnit = GeographyUnit.DecimalDegree;
            wpfMap1.CurrentExtent = new RectangleShape(-155.733, 95.60, 104.42, -81.9);

            WorldMapKitWmsWpfOverlay worldMapKitOverlay = new WorldMapKitWmsWpfOverlay();
            wpfMap1.Overlays.Add(worldMapKitOverlay);

            markerOverlay = new InMemoryMarkerOverlay();
            markerOverlay.Columns.Add(new FeatureSourceColumn("Name"));
            markerOverlay.ZoomLevelSet.ZoomLevel01.DefaultPointMarkerStyle.ImageSource = new BitmapImage(new Uri("/Resources/AQUA.png", UriKind.RelativeOrAbsolute));
            markerOverlay.ZoomLevelSet.ZoomLevel01.DefaultPointMarkerStyle.Width = 20;
            markerOverlay.ZoomLevelSet.ZoomLevel01.DefaultPointMarkerStyle.Height = 34;
            markerOverlay.ZoomLevelSet.ZoomLevel01.DefaultPointMarkerStyle.YOffset = -17;
            markerOverlay.ZoomLevelSet.ZoomLevel01.DefaultPointMarkerStyle.ToolTip = "This is [#Name#].";
            markerOverlay.ZoomLevelSet.ZoomLevel01.ApplyUntilZoomLevel = ApplyUntilZoomLevel.Level20;
            wpfMap1.Overlays.Add("MarkerOverlay", markerOverlay);

            Feature newFeature = new Feature(-95.2806, 38.9554);
            newFeature.ColumnValues.Add("Name", "Lawrence");

            markerOverlay.FeatureSource.BeginTransaction();
            markerOverlay.FeatureSource.AddFeature(newFeature);
            markerOverlay.FeatureSource.CommitTransaction();

            wpfMap1.Refresh();
        }

        private void wpfMap1_MapClick(object sender, MapClickWpfMapEventArgs e)
        {
            Collection<Feature> nearestFeatures = markerOverlay.FeatureSource.GetFeaturesNearestTo(e.WorldLocation, GeographyUnit.DecimalDegree, 1, ReturningColumnsType.AllColumns);
            if (nearestFeatures.Count > 0)
            {
                // or we can set a tolerence
                double tolerence = 1000;
                double distance = DecimalDegreesHelper.GetDistanceFromDecimalDegrees(new Feature(e.WorldLocation), nearestFeatures[0], DistanceUnit.Kilometer);
                if (distance < tolerence)
                {
                    MessageBox.Show("Selected Feature:" + nearestFeatures[0].GetWellKnownText());
                }
            }
        }